Energy drinks have long been billed to be as safe as a cup of coffee, but lately they’ve collectively come under fire for being little more than stimulant-loaded health hazards. The problem boils down to the fact that these beverages are considered as dietary supplements, and as such they are not required to indicate the amount of caffeine or other energy-imparting ingredients contained in their formulations. At present, there have been a total of 92 patient reports linked to 5-Hour Energy, including 13 deaths and 33 hospitalizations for serious and life-threatening conditions, including heart attacks and convulsions.

The allegations, which date back to 2004, don’t conclusively prove a causal link to the deaths, however, following five deaths associated with Monster energy drink in October, Senators Richard Durbin (D-IL) and Richard Blumenthal (D-CT) called upon FDA for the third time this year to close what they considered to be loopholes allowing energy-drink makers to sell products with additives and high levels of caffeine that have not been proven safe. They also requested that the agency take a closer look at other stimulant ingredients used in addition to caffeine in energy beverage formulation, as well as the risk the beverages pose to teens who consume them.

And finally, Senators Durbin and Blumenthal presented data from Consumer Reports, which tested 27 top-selling energy drinks and shots and found caffeine amounts ranging from 6 mg to 242 mg per serving. FDA limits the amount of caffeine in soda to 0.02%, but there is currently no limit for energy drinks. By comparison, a 24-oz. can of Monster Energy Drink contains 240 mg of caffeine—seven times the caffeine as a 12-oz. can of ordinary cola.

Consumer Reports found the product with the highest level of caffeine was 5-hour Energy Extra Strength (1.9 fl. oz. with 242 mg caffeine) and the lowest was 5-hour Energy Decaf (1.9 fl. oz. with 6 mg caffeine). An 8-oz. cup of coffee has about 100 mg of caffeine and a 16-oz. Starbucks Grande had about 330 mg of caffeine.

“Five of the 16 products that list a specific amount of caffeine—Arizona Energy, Clif Shot Turbo Energy Gel, Nestlé Jamba, Sambazon Organic Amazon Energy, and Venom Energy—had more than 20 percent above their labeled amount on average in the samples we tested,” Consumer Reports wrote. “On the other hand, one of our three samples of Archer Farms Energy Drink Juice Infused had caffeine about 70 percent below the labeled amount. For the other drinks that list caffeine levels, the actual numbers were within 20 percent of claimed, which we think is an acceptable range for meeting caffeine claims.”

Curiously, 11 of the 27 drinks didn’t specify the amount of caffeine in their formulations. Consumer Reports said perhaps proprietary blends of amino acids, carbohydrates or guarana could have been the cause. A representative of the Monster Beverage Corporation gave the group another reason: they don’t have to. “There is no legal or commercial business requirement to do so, and also because our products are completely safe, and the actual numbers are not meaningful to most consumers,” the company told Consumer Reports.

And that’s the rub: energy beverages, sold alongside colas and juices, aren’t legally required to specify how much caffeine they contain, yet 16 of the 27 products tested by Consumer Reports bore warnings cautioning use by children, pregnant or nursing women and people sensitive to caffeine. The Monster drinks and eight others also specified a daily limit.

“Safe limits of caffeine consumption are still being studied, but data suggest that most healthy adults can safely consume up to 400 milligrams per day; pregnant women, up to 200 milligrams; and children, up to 45 to 85 milligrams depending on weight,” Consumer Reports wrote. “An occasional energy drink is probably fine for most adults.”

The beverages might be safe in moderation but their potential for danger has caught the attention of New York state Attorney General Eric Schneiderman, who last August issued subpoenas to energy-drink makers Monster Beverage, PepsiCo (AMP) and Living Essentials (5-hour Energy) to determine if the companies were misleading consumers about caffeine levels and health risks the beverages could pose.

Daniel Fabricant, PhD, the director of the FDA’s division of dietary supplement programs, told the New York Times the FDA was looking into the death reports that cited 5-Hour Energy. He said that while medical information could rule out a link with the product, other reports could contain insufficient information to determine what role, if any, a supplement might have played. It’s worth noting that in addition to caffeine, 5-hour Energy also contains high levels of B vitamins and taurine.

In comments provided to Nutraceuticals World, FDA Spokeswoman Shelly Burgess said the FDA is continuing to monitor the energy drink situation, especially as it relates to reports of illness, injury or death connected to the consumption of 5-hour Energy products. “If we find a relationship between consumption of the product and harm, FDA will take appropriate action to reduce or eliminate the risk,” Ms. Burgess said.